In our previous work, we were concerned with the question of how to calculate the concentration noise power spectrum of linear kinetic systems when the rate constants of the systems are assumed to be known and the question of how to evaluate the rate constants of the reactions when adequate noise data are available. In our current work, we have extended our analysis to systems with non-linear kinetic reactions. Non-linear chemical reactions are very common in biochemistry. For example, the association-dissociation reactions of multi-subunit systems such as hemoglobins and oligomeric enzymes, or most enzymatic reactions are non-first order reactions. In general, with the use of a "quasi-linearization" approximation, the phenomenological relaxation matrix, the variances, and the resulting noise power spectrum are all expressed in terms of the usual kinetic rate terms of the chemical mass action law. Thus, the calculation of the noise power spectrum becomes very simple as soon as the rate constants of all elementary reactions of the system are known. The formalism can be used as well to evaluate the rate constants of the elementary reactions. BIBLIOGRAPHIC REFERENCES: Chen, Yi-der: Fluctuations and noise in non-linear kinetic systems. J. Theoret. Biol. 65: 357-367, 1977. Chen, Yi-der: The irreversible thermodynamic approach to the fluctuations in chemical reactions. J. Chem. Phys. 66: 2431-2434, 1977.